SE462583 describes a method and an apparatus for dehumidification of air wherein process air is dehumidified through passing a drying rotor comprising moisture adsorbing means. In order to reach high temperatures radiation heat is used from a heating element, for example a radiator, for regeneration of a rotor by means of an adsorption means.
During dehumidification the user can have different requests regarding what to be obtained: for example to remove water as energy efficiently as possible, to remove as much water as possible per time unit or to create air with as low vapour content as possible. These different requests, or operation modes, require different parameter settings of the dehumidification device. These parameter settings may relate to the rotational speed of the fan or fans transporting air through the dehumidifier, power input to the heating element, distribution of incoming air between outgoing dry air and regeneration air etc.
A technician with long experience can finally learn approximate settings which give a desired operation mode, but even such experienced technicians may not always set optimum values for the operation parameters.
One kind of heating element is the so-called PTC heater, where PTC stands for Positive Temperature Coefficient. These heating elements have the feature that the power they deliver depends on the amount of air flowing by, i.e., the air velocity, as well as the temperature of the air flowing by. This means for example that a PTC heater wherein no air flows by outputs essentially no power.